ISLE OF MAN. ALLUVIA. 525 



the steepness of the declivity and the rapidity of the 

 water, a quantity of rubbish, forming a beach of rounded 

 pebbles, has been accumulated at the mouths of the 

 streams : but it is generally insignificant in extent; making 

 no permanent addition to the land, and producing no 

 effect in changing the forms of the shores at the exits 

 of the water. The operations of the mountain streams 

 in some situations, and among others in the higher parts 

 of Baldwin valley, upon the mountain alluvia, is rather 

 more remarkable ; since they are in these places skirted by 

 the flat terraces of rubbish which so often accompany the 

 course of a river that cuts its way through these accumu- 

 lations of loose materials. 



These alluvia are found on the lower parts of the slopes 

 of the hills and in the bottoms of the valleys, all over the 

 island. Their origin cannot apparently be traced, either 

 to the present or former action of rivers ; since they are 

 equally deep and predominant even where water could 

 never have flowed. Nor is there much evidence of a dilu- 

 vian origin, a cause, the operations of which are so fre- 

 quently to be traced in the mountainous parts of Scotland 

 as well as on the great plains of England; and which 

 may perhaps have given rise to another deposit in this 

 island that will be immediately described. Such however 

 may, at least in some degree, have been the origin of 

 many of these and similar alluvia ; for which, the gradual 

 wearing: and descent of the surfaces and summits of the hills 



O 



towards the valleys, offer but an inadequate explanation. 

 Without such a general cause, it is impossible to explain 

 the existence of granite boulders ; nor indeed of the 

 rounded materials which enter into the alluvial deposits 

 together with the angular fragments that appear to have 

 undergone but a limited transportation ; which latter, from 

 their similarity of texture to the neighbouring rocks, 

 appear to lie nearly in the places where they were 

 formed. But I must leave this difficult question unde- 

 termined, and turn to another of the conspicuous parts 



